Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Strong-Acid Weathering in a Carbonate-Siliciclastic Cropland Diminishes Removal of CO2 From the Atmosphere Without Becoming a CO2 Source","authors":"Michael J. Forgeng,&nbsp;Jonathan M. Duncan,&nbsp;Caitlin A. Hodges,&nbsp;Jason Kaye,&nbsp;Brandon Forsythe,&nbsp;Timothy S. White,&nbsp;Susan L. Brantley","doi":"10.1029/2025JG009418","DOIUrl":"https://doi.org/10.1029/2025JG009418","url":null,"abstract":"<p>One strategy to remove carbon dioxide (CO₂) from the atmosphere is to accelerate weathering in croplands by adding powdered rock. Both silicate and carbonate minerals can be effective as amendments, but strong acids from rain and fertilizer diminish CO₂ removal and can promote degassing of CO₂ from carbonate minerals (geogenic CO₂). In addition, denitrification of fertilizer inputs releases dissolved inorganic carbon that could promote re-precipitation of calcite. To investigate these processes, we used synoptic sampling and analysis of chemistry, dual nitrate isotopes, and solute loads in waters from a 168 km² humid-temperate agricultural catchment on siliciclastic and carbonate lithologies receiving sulfuric-and nitric-acid inputs. We explored (a) whether strong-acid dissolution of carbonate minerals became a source of atmospheric CO₂, (b) whether strong acids diminished CO₂-driven weathering, and (c) whether calcite precipitation (with possible CO₂ degassing) accompanied denitrification. We saw no evidence of carbonate weathering as a source of CO₂ in the atmosphere. Carbonate weathering was not a CO₂ source mainly because alkalinity remained high and pH stayed above six except in silicate-dominated terrain. Weathering removed CO₂ from the atmosphere: 2.3 ± 2.0 mmol km⁻² s⁻¹ for silicate-rich uplands and 21 ± 9 mmol km⁻² s⁻¹ for carbonate-rich lowlands. This drawdown was 22% and 12% less, respectively, than a non-acidified counterfactual. The silicate-versus-carbonate difference in diminishment of CO₂ drawdown reflects slow silicate versus fast carbonate dissolution. Removal of nitrate by denitrification and biotic uptake ameliorated some of the effects of strong acids but may also have driven calcite re-precipitation downstream.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 10","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009418","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal and Spatial Variability of Silicon Cycle in Godavari Tidal River Zone","authors":"Sarath Pullyottum Kavil,&nbsp;Jean Riotte,&nbsp;Ramananda Chakrabarti,&nbsp;V. V. S. S. Sarma,&nbsp;Arnaud Dapoigny,&nbsp;Gilles Reverdin,&nbsp;Damien Cardinal","doi":"10.1029/2025JG009437","DOIUrl":"https://doi.org/10.1029/2025JG009437","url":null,"abstract":"<p>Dam regulation of tropical monsoonal rivers enhances seasonal contrasts in the tidal river zone (TRZ) hydrology, altering the delivery of dissolved silicon (DSi) to the coastal ocean. Here, we identify the drivers of Si cycling in the Godavari TRZ and quantify their implications for Si delivery to the Bay of Bengal (BoB). We analyzed elemental concentrations and isotopic tracers (δ³⁰Si, δ¹⁸O, δ²H,⁸⁷Sr/⁸⁶Sr) of the water column and adjacent groundwater during dry (pre-monsoon) and wet (monsoon) seasons to delineate mixing and biogeochemical processes in the Godavari TRZ. During the dry season, deviations from the river water-seawater binary mixing line for ⁸⁷Sr/⁸⁶Sr and δ¹⁸O indicate groundwater input, ranging from 7% to 43% across TRZ stations. We observe non-conservative mixing of DSi and δ³⁰Si values during the dry season, with a significant DSi removal (20%–85%) and enrichment in δ³⁰Si values. The dominance of diatoms in suspended matter and elevated concentrations of the diatom marker pigment fucoxanthin confirm the role of biological uptake in DSi removal. Closure of the Dowleiswaram dam during the dry season reduces river discharge, increases water residence time in the TRZ, and promotes diatom growth. In contrast, the opening of dam gates during the monsoon season, when catchment precipitation is at its peak, leads to high river water influx into the TRZ and elevated suspended matter concentrations (175 ± 50 mg/L), limiting diatom growth during the wet season. Annually, the Godavari River supplies 22.1 ± 5.1 Gmol of Si with a flux-weighted δ³⁰Si composition of 1.2‰ ± 0.1‰ to the BoB, of which approximately 19% is converted into biogenic silica by diatoms during low discharge periods. The estimated isotopic enrichment associated with this diatom uptake is negligible. The annual groundwater-derived Si flux to the Godavari TRZ is 0.8 ± 0.5 Gmol Si, representing ∼3.5% of the annual riverine Si flux; however, during the dry season, groundwater constitutes the dominant local Si source within the TRZ, accounting for 47%–79% of the total Si flux, depending on the station.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 10","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009437","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149140475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effects of Stream Slope on Dissolved Gas Concentrations Are Mediated by Scale in an Example Low-Gradient Stream","authors":"Yuseung Shin,&nbsp;Nicholas S. Marzolf,&nbsp;Nguyen Tien Anh Quach,&nbsp;Heili E. Lowman,&nbsp;Adam Rok,&nbsp;Emily S. Bernhardt,&nbsp;Amanda G. DelVecchia","doi":"10.1029/2026JG009786","DOIUrl":"https://doi.org/10.1029/2026JG009786","url":null,"abstract":"<p>Channel slope influences the key physical and biogeochemical drivers of dissolved gas dynamics in flowing waters, including turbulence-driven gas exchange, in situ metabolism, and external inputs. These processes operate at different spatial scales, yet the extent to which channel slope controls longitudinal gas concentration variations—particularly in low-gradient streams containing pools with high hydrologic retention—remains poorly understood. In this study, we measured dissolved oxygen (DO), carbon dioxide (CO₂), and methane (CH₄) along a ∼8 km stretch of New Hope Creek (NHC), a low-gradient stream in North Carolina characterized by frequent pools. We paired longitudinally collected gas concentrations with estimates of gas transfer velocity (<i>k</i>₆₀₀) and channel slopes. We measured substantial spatial variation in the concentrations of all three gases, but this variation was not significantly correlated with <i>k</i>₆₀₀, which was low across sites (0.10–15.33 m d⁻¹, median = 0.35 m d⁻¹). Instead, channel slope was a better predictor. A flatter slope was associated with greater departure from equilibration (depletion for DO and oversaturation for GHGs), but the relationship occurred at different scales: habitat (∼50 m) for DO and long-distance scale (&gt;100 m) for GHGs. However, during high-flow periods enhancing mixing, we measured minimal spatial variation. These results demonstrate that channel slope controls longitudinal gas concentration patterns by influencing biogeochemical processes at varying distances. Our study showed that gas exchange coefficients might not encompass the full reach-scale variations and underscored the importance of geomorphic context in shaping the longitudinal heterogeneity of dissolved gases in low-gradient streams.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 10","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149068109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydraulic Trait Strategies Lead to Divergent Tree Growth Responses to Multidecadal Climate Variability","authors":"Sarah E. Bungard,&nbsp;Gil Bohrer,&nbsp;Jason M. Tallant,&nbsp;Christopher M. Gough,&nbsp;Kyungmin Sung,&nbsp;James H. Stagge,&nbsp;John D. Lenters,&nbsp;Christoph S. Vogel,&nbsp;Lucas E. Nave,&nbsp;Jeff W. Atkins,&nbsp;Aimée T. Classen","doi":"10.1029/2026JG009928","DOIUrl":"https://doi.org/10.1029/2026JG009928","url":null,"abstract":"<p>Climate change, including altered precipitation patterns, is impacting the growth, competition, survival, and carbon allocation dynamics of trees globally. Using 22 years of data, we aimed to link the strength and timing of species-specific stem growth responses to water stress and species-level hydraulic strategy traits. We measured gross primary production (GPP) as well as environmental factors including soil water content, vapor pressure deficit, and photosynthetically active radiation within the footprint of the AmeriFlux US-UMB site, a temperate deciduous forest in northern Michigan. We recorded annual stem growth increments of individuals encompassing eight species using band dendrometers and calculated annual changes in biomass using allometric equations. Yearly stem growth for each species was compared to mean environmental conditions over 3-month seasonal periods from the same and previous year to account for potential lags between climate and growth signals. At the ecosystem level, no correlation between measured changes in aboveground biomass and GPP was observed for the current and prior years, suggesting divergent temporal carbon allocation patterns that vary among species. In our forest site, the growth of white pine was negatively correlated with growing season soil water content, in contrast to most measured species, indicating that drought affected the competitive interactions of species with different hydraulic traits. These contrasting trends and asynchrony with GPP reiterate the need for consideration of hydraulic trait strategies in carbon modeling.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 10","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149068108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraints on Ocean Alkalinity Enhancement: Limited Olivine Dissolution and Secondary Precipitation During Periclase Addition to Seawater","authors":"Shreya Mehta,&nbsp;Sipai Nazirahmed,&nbsp;Jitender Kumar,&nbsp;Himanshu Saxena,&nbsp;Sanjeev Kumar,&nbsp;Vinaya Kumar Vase,&nbsp;S. Chinnadurai,&nbsp;Arvind Singh","doi":"10.1029/2026JG009977","DOIUrl":"https://doi.org/10.1029/2026JG009977","url":null,"abstract":"&lt;p&gt;Ocean alkalinity enhancement (OAE) is a proposed carbon dioxide removal strategy. Although several methods have been proposed for OAE, a systematic assessment of the mineral-based alkalinity generation potential, along with the associated carbonate chemistry and biogeochemical responses to alkalinity additions, is not fully constrained. Previous studies indicate a high alkalinity generation potential of periclase and limited dissolution of olivine. We conducted a 9-day mineral-based mesocosm experiment to evaluate the potential of periclase and olivine for OAE across a broader range of targeted alkalinity additions: periclase (P1: +500, P2: +1,000, P3: +1,500, and P4: +2,000 μmol &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mtext&gt;kg&lt;/mtext&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{kg}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) and olivine (O1: +250, O2: +500, O3: +750, and O4: +1,000 μmol &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mtext&gt;kg&lt;/mtext&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{kg}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;). Olivine additions did not result in measurable changes in alkalinity or pH, likely due to high dissolved organic matter, high pH, and limited mixing over time. In contrast, for periclase treatments (P1–P4), alkalinity increased by ∼200, ∼450, ∼447, and ∼463 μmol &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mtext&gt;kg&lt;/mtext&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{kg}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, while pH increased by 0.31, 0.42, 0.60, and 0.59, respectively. Dissolved inorganic carbon (DIC) declined within the first 24 hr in P2, P3, and P4, with alkalinity decreasing subsequently after day one. This decline in DIC, together with the isotopic signature of DIC (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;δ&lt;/mi&gt;\u0000 &lt;mn&gt;13&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;C&lt;/mi&gt;\u0000 &lt;mtext&gt;DIC&lt;/mtext&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${delta }^{13}{mathrm{C}}_{text{DIC}}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;), revealed that secondary precipitation dominated at alkalinity additions of &lt;","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Continental to Meter Scale Climatic, Topographic, and Geomorphological Gradients Control Soil Organic Carbon Distribution in Complex Arctic Terrain","authors":"Elis Ingvarsson,&nbsp;Cristian Gudasz,&nbsp;Matthias B. Siewert","doi":"10.1029/2025JG009598","DOIUrl":"https://doi.org/10.1029/2025JG009598","url":null,"abstract":"<p>Arctic soils store large amounts of soil organic carbon (SOC), yet landscape-scale variability remains poorly constrained, especially in complex mountainous regions that can be found across the Arctic. Understanding climate change impacts on Arctic carbon dynamics requires in-depth knowledge of SOC controls, given multiple drivers and potential responses. We map and quantify SOC stocks at the-scale in a large catchment in the Swedish Arctic and evaluate environmental controls of SOC distribution. A total of 310 georeferenced soil profiles were compiled, and SOC stocks were modeled using a machine learning approach trained on 14 environmental predictors. Predicted SOC stocks showed substantial spatial variation, ranging from 0 to 145.1 kg C m⁻², with a catchment-wide mean (±SD) of 4.8 ± 7.0 kg C m⁻². Organic layers, including deep peat deposits, accounted for 48% of the total SOC. Two dominant gradients structured SOC distribution: (a) as the climate in the catchment transitions from maritime to continental (west to east), SOC storage increases substantially due to peatland formation; and (b) a topographic gradient promotes substantially more SOC storage in valley bottoms and depositional slopes compared to uplands and mountaintops. Further, we reveal considerable variation at meter scale due to the geomorphological complexity of the landscape. We show that SOC variability in Arctic-mountainous regions is strongly controlled by the hierarchical interaction between climate, topography, and fine-scale geomorphology. Resolving these drivers at very high spatial resolution underscores the importance of landscape-scale analyses across environmental gradients for assessing the sensitivity of Arctic SOC stocks to ongoing climate change.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009598","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling Dynamics of Hydrogen-Oxidizing Bacteria Under Pulsing Soil Moisture Conditions","authors":"Damola Olaitan,&nbsp;Matteo B. Bertagni,&nbsp;Amilcare Porporato","doi":"10.1029/2026JG010003","DOIUrl":"https://doi.org/10.1029/2026JG010003","url":null,"abstract":"<p>Hydrogen-oxidizing bacteria (HOB) are responsible for the dominant soil sink of atmospheric hydrogen (H₂); however, models estimating this sink are yet to incorporate explicit representation of these biotic drivers. Here, we use a donor-consumer model to examine how HOB and carbon-decomposing bacteria (CDB) may jointly influence organic carbon decomposition and atmospheric H₂ uptake as critically driven by hydroclimatic forcings and temporally varying soil moisture. Hydroclimatic forcing was investigated through three simulation setups: constant soil moisture, drying-wetting sequences, and intermittent rainfall. Collectively, these simulations suggest the coexistence of both HOB and CDB, with each group predominantly contributing to microbial biomass in low and high soil moisture regions, respectively. Given the strong influence of soil moisture on H₂ uptake identified in this study, our results further suggest that explicit representation of biotic drivers (HOB biomass and soil carbon) amplifies the oscillatory dynamics in soil H₂ concentration, a feature not captured by the abiotic-only model. We further examined the hypothesis that dormant microbes scavenge H₂ as a survival mechanism by incorporating microbial dormancy into the HOB dynamics and showed that dormancy leads to a higher biomass contribution of HOB in arid regions (dryness index &gt; 5). Finally, the model was applied to estimate H₂ deposition velocity, showing improved agreement with measured data from a temperate forest and validating the importance of the explicit representation of biotic drivers. Model limitations and the potential integration with land-surface models are also discussed.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG010003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Top-Down and Bottom-Up Drivers of Soil δ15N Spatial Patterns in a Tropical Savanna","authors":"Yong Zhou,&nbsp;Corli Coetsee","doi":"10.1029/2026JG010008","DOIUrl":"https://doi.org/10.1029/2026JG010008","url":null,"abstract":"<p>Although stable nitrogen isotopes (δ¹⁵N) can provide a powerful integrative tracer of localized nutrient cycling across heterogeneous savannas, the relative influence of top-down versus bottom-up drivers in shaping these spatial patterns remains largely unresolved. Here, we leveraged long-term monitoring and extensive spatial sampling of 253 sites across a tropical savanna in Kruger National Park, South Africa. By applying a Generalized Additive Model (GAM) and variance partitioning, we evaluated the distinct contributions of top-down disturbances (fire and herbivory) and bottom-up drivers (vegetation structure, soil properties, topography, and climatic variables). Our model explained 60.9% of total deviance and revealed high spatial heterogeneity in soil δ¹⁵N (2.99–9.07‰). Variance partitioning demonstrated that bottom-up drivers overwhelmingly governed spatial variation, driven predominantly by two factors: first, the non-linear effects of high N-fixing tree cover, which dilute soil δ¹⁵N with depleted atmospheric N; and second, increasing soil C:N ratios, which potentially slow mineralization and consequently limit fractionating N losses. Conversely, top-down drivers, while traditionally central to savanna ecology, played a comparatively minor role, primarily limited to the local enriching effects of extended fire-free intervals. Furthermore, the patterns predicted by the GAM model highlight localized hotspots of ¹⁵N enrichment alongside broader spatial trends in soil δ¹⁵N that contrast sharply with total soil N. Ultimately, our study demonstrates that spatial variation in savanna soil δ¹⁵N is primarily dictated by localized bottom-up drivers rather than top-down disturbances, suggesting these local factors act as strong proxies for the underlying biogeochemical processes shaping savanna N cycling.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG010008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated Daily Measurements of Soil Pore Space CO2 and O2: Signals Revealing Soil Physical and Biogeochemical Processes","authors":"Timothy M. Gallagher,&nbsp;Jason Dahlberg,&nbsp;Kyle E. Smart,&nbsp;Nicole Czwakiel,&nbsp;Morgan Mellum,&nbsp;Daniel O. Breecker","doi":"10.1029/2026JG010119","DOIUrl":"https://doi.org/10.1029/2026JG010119","url":null,"abstract":"<p>There is a need to understand and monitor active soil processes in the field; however, it is challenging to observe and separate co-occurring belowground processes. High precision monitoring of soil pore space gases is a potentially powerful approach, complicated by the variety of biological and physical processes that impact gas. To evaluate processes controlling soil CO₂ and O₂ concentrations across weekly to seasonal timescales, we installed a custom-built automated gas sampling system outside of Bastrop, Texas that enabled field-based, high-precision measurements of soil CO₂ and O₂ concentrations for over a year. We focus on the ratio of soil-atmosphere differences in CO₂ and O₂ concentrations, referred to as the apparent respiratory quotient (ARQ). Rainfall events physically modified soil gas signals by driving short-term (2–5 day) transient decreases in ARQ values throughout the soil profile. Filtering out data impacted by transient effects allows seasonal soil gas signals to emerge, illustrating the dominance of root respiration and microbial respiration of plant derived carbohydrates during the growing season. Systematically higher ARQ values were observed during the dry summer and fall, whereas lower ARQ values predominated during the wet and cold winter months. We consider that a shift in microbial carbon-use efficiency is the most likely driver of high ARQ values during the dry season as autotrophic respiration slows. The low winter ARQ signals could be driven by a number of different processes such as respiration of more reduced substrates, increased nitrification rates, or metal oxidation.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG010119","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intensive Nutrient Input Strengthens the Organic Carbon Sequestration Potential in Fishpond Sediments","authors":"Hezhong Yuan,&nbsp;Qianhui Yuan,&nbsp;Tong Guan,&nbsp;Enfeng Liu,&nbsp;Yu Wang,&nbsp;Jianghua Yu,&nbsp;Yuqi Liu,&nbsp;Jie Yan,&nbsp;Mingjing Sun,&nbsp;Xudong Wu,&nbsp;Qingfei Zeng","doi":"10.1029/2026JG009970","DOIUrl":"https://doi.org/10.1029/2026JG009970","url":null,"abstract":"<p>Burial in sediments as organic carbon (OC) is the key pathway for C reduction. However, the C fixation mechanisms in fishpond sediments remain unclear. In this study, sediments were taken from fishponds raising different fish species. Different OC fractions including microbial biomass C (MBC), enzymatic activities, and C uptake indices including microbial C use efficiency (CUE) were obtained. The microbial communities were identified using 16S rRNA high-throughput sequencing. The genes, cbbL and cbbM, encoding Calvin-Benson-Bassham (CBB) cycle were analyzed to decipher the community assembly regulation of C-fixing bacteria. Results indicated that the fishpond cultivating Channel catfish had higher OC and nutrients. Higher MBC and C uptake factors indicated that high nutrients facilitated MBC synthesis and OC burial via microbial activities. Different from enzymes involved in C and N cycles, alkaline phosphatase (AP) displayed a significantly positive correlation with OC fractions. This cooperativity revealed that AP dominated the organic phosphorus mineralization and phosphate increase in water, thereby promoting C assimilation and burial into sediments. Additionally, 16S rRNA and CBB cycle genes revealed that the microbial community structure remarkably varied with fishpond types. The nutrient-rich fishpond exhibited a greater abundance of dominant bacterial genera. Aquaculture types coupling nutrient differences induced the microbial community regulation, which further triggered the CUE response and MBC enrichment. Generally, nutrient-driven MBC accumulation and microflora shifts were key drivers of OC sequestration. These findings provide new insights into the mechanisms of OC fixation in fishponds and suggest potential Nature-based Solutions for enhancing global C reduction management.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 9","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}